Perhaps this has been asked numerous times before .

I would really appreciate if some one can generously point out to me the places where I can find good Application Notes and Technical Literature on Modbus and Lonworks.

More questions :

1)Are these very widely used in automation industry?
2)How long have they been around and any danger of being superseded
or obsoleted ?
3)Are these proprietary or open standards ?

There are a number of Serial-Interface LCD Modules that operate on RS232 and
RS485 standards : can these be linked via these Modbus / Lonworks ?

Many thanks from a newbie.

Thank you in advance,
Alex

 

Hi,

The two protocols you mentioned are somewhat like apples and oranges, cannot be compared. They serve different need and have quite entirely different characteristics. A very brief comparison:

Business:
MODBUS is just a definition (and free to use) - on a serial (RS323, 485 or 422, and even on Ethernet). There are a lot of products as well.
Lon is a proprietary protocol of the Lon company - and you can only use it by purchasing a license from Echelon and special chips - or by using a
Lon-compatible product.

Engineering
MODBUS is master-slave and transports raw bits (one to approx. 1600) and 16-bit words (one to approx. 100) Lon is peer-to-peer and transforms various engineering type (scaled) and named data items.

So I suggest you first define what you need, then proceed
For Modbus, see www.modicon.com
for Lon, see www.echelon.com

Meir C. Saggie Chief Engineer
AFCON Control and Automation Ltd., P.O.BOX 3120 Petach Tikva, Israel, 49130

T: +972-3-9392404 F: +972-3-9244249 E: <[email protected]>
W: http://www.afcon-inc.com

 

Alex,

You can find all of Echelon's technical literature and application notes in
soft format on our website at http://www.echelon.com/products.

To answer your questions :

1) Yes LonWorks is widely found in the automation industry. If you look
through the third party resource directory, you will find numerous products
designed for that purpose - see http://www.echelon.com/solutions/

2) Echelon and LonWorks has been around for about 10 years now. Echelon is
a worldwide organization and the LonWorks technology is built into
everything from medical equipment, to transportation (ships, planes, trains
etc), to Building Automation Systems, to Home Automation Systems, to factory
process control equipment.... etc. Echelon and LonWorks is here to stay.

3)Yes LonWorks is an open standard. LONWORKS has been included in many
international standards including IEEE 1473 (train control), ANSI/EIA 709.1
(control networks), TC247 (building automation), AAR (electro-pneumatic
train braking), and the SEMI standard (semiconductor manufacturing
equipment). Its inclusion in so many international standards has validated
LONWORKS as an open standard. Likewise, its use by thousands of
manufacturers, across many industries, has proven the utility of LONWORKS
for a wide range of applications.

4) There are a variety of ways to link a serial device to a LonWorks
network. The Neuron chip itself does have a low speed serial interface,
Echelon makes a serial to LonWorks device called the SLTA-20 (Serial LonTalk
Adapter), and there are third party devices that do the same.

I hope this helps, please don't hesitate to write if you have additional
questions.

Regards,

Fred Graham, Field Applications Engineer
Echelon
10945 Statebridge Rd, Suite 401 PMB-305
Alpharetta, GA 30022
770-887-9024 (voice)
770-886-0547 (fax)
mailto: [email protected]

 

Meir,

I must correct you on part of your statements. The LonTalk protocol, while it is developed by Echelon, does not require that you purchase a license. The protocol is licensed but at no charge. The license requires that you fully implement the protocol and make sure it is compatible with the current implementation (which is the Neuron chip). This prevents the fiasco that happened with the many variations of UNIX. The protocol specification is available (EIA 709.1) and a reference implementation is available for free at Echelon's website - http://www.echelon.com. If you don't feel like porting the protocol, you can purchase chips, known as Neuron Chips, from multiple sources that have a full implementation of the protocol. The advantage of purchasing the silicon is that the protocol is already implemented and tested.

As for the Engineering points, LonWorks can deliver raw data as easily as any other data. The LonMark Interoperability Association (
http://www.lonmark.org ) is a user organization that defines interoperability guidelines for LonWorks products. They do have a list of standard data types that can be used in order to help facilitate interoperability, but you don't have to use them if you aren't interested in sharing data. Look at it another way, if I send raw data, you can't know how to interpret that data and what it means. If I use a predefined data type such as SNVT_temp (Standard Network Variable Type_ temperature, which is defined as degrees C with a defined range and resolution), then there is no issue of misinterpretation and I can share that data with any other LonWorks device without having to talk to another manufacturer.

Hope this clears up any confusion.

Regards,

Fred Graham, Field Applications Engineer
Echelon
10945 Statebridge Rd, Suite 401 PMB-305
Alpharetta, GA 30022
770-887-9024 (voice)
770-886-0547 (fax)
mailto: [email protected]